text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  HID support for Linux
   *
   *  Copyright (c) 1999 Andreas Gal
   *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
   *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
   *  Copyright (c) 2006-2012 Jiri Kosina
   */
  
  /*
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/mm.h>
  #include <linux/spinlock.h>
  #include <asm/unaligned.h>
  #include <asm/byteorder.h>
  #include <linux/input.h>
  #include <linux/wait.h>
  #include <linux/vmalloc.h>
  #include <linux/sched.h>
  #include <linux/semaphore.h>
  
  #include <linux/hid.h>
  #include <linux/hiddev.h>
  #include <linux/hid-debug.h>
  #include <linux/hidraw.h>
  
  #include "hid-ids.h"
  
  /*
   * Version Information
   */
  
  #define DRIVER_DESC "HID core driver"
  
  int hid_debug = 0;
  module_param_named(debug, hid_debug, int, 0600);
  MODULE_PARM_DESC(debug, "toggle HID debugging messages");
  EXPORT_SYMBOL_GPL(hid_debug);
  
  static int hid_ignore_special_drivers = 0;
  module_param_named(ignore_special_drivers, hid_ignore_special_drivers, int, 0600);
  MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special drivers and handle all devices by generic driver");
  
  /*
   * Register a new report for a device.
   */
  
  struct hid_report *hid_register_report(struct hid_device *device,
  				       unsigned int type, unsigned int id,
  				       unsigned int application)
  {
  	struct hid_report_enum *report_enum = device->report_enum + type;
  	struct hid_report *report;
  
  	if (id >= HID_MAX_IDS)
  		return NULL;
  	if (report_enum->report_id_hash[id])
  		return report_enum->report_id_hash[id];
  
  	report = kzalloc(sizeof(struct hid_report), GFP_KERNEL);
  	if (!report)
  		return NULL;
  
  	if (id != 0)
  		report_enum->numbered = 1;
  
  	report->id = id;
  	report->type = type;
  	report->size = 0;
  	report->device = device;
  	report->application = application;
  	report_enum->report_id_hash[id] = report;
  
  	list_add_tail(&report->list, &report_enum->report_list);
  
  	return report;
  }
  EXPORT_SYMBOL_GPL(hid_register_report);
  
  /*
   * Register a new field for this report.
   */
  
  static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
  {
  	struct hid_field *field;
  
  	if (report->maxfield == HID_MAX_FIELDS) {
  		hid_err(report->device, "too many fields in report\n");
  		return NULL;
  	}
  
  	field = kzalloc((sizeof(struct hid_field) +
  			 usages * sizeof(struct hid_usage) +
  			 values * sizeof(unsigned)), GFP_KERNEL);
  	if (!field)
  		return NULL;
  
  	field->index = report->maxfield++;
  	report->field[field->index] = field;
  	field->usage = (struct hid_usage *)(field + 1);
  	field->value = (s32 *)(field->usage + usages);
  	field->report = report;
  
  	return field;
  }
  
  /*
   * Open a collection. The type/usage is pushed on the stack.
   */
  
  static int open_collection(struct hid_parser *parser, unsigned type)
  {
  	struct hid_collection *collection;
  	unsigned usage;
  	int collection_index;
  
  	usage = parser->local.usage[0];
  
  	if (parser->collection_stack_ptr == parser->collection_stack_size) {
  		unsigned int *collection_stack;
  		unsigned int new_size = parser->collection_stack_size +
  					HID_COLLECTION_STACK_SIZE;
  
  		collection_stack = krealloc(parser->collection_stack,
  					    new_size * sizeof(unsigned int),
  					    GFP_KERNEL);
  		if (!collection_stack)
  			return -ENOMEM;
  
  		parser->collection_stack = collection_stack;
  		parser->collection_stack_size = new_size;
  	}
  
  	if (parser->device->maxcollection == parser->device->collection_size) {
  		collection = kmalloc(
  				array3_size(sizeof(struct hid_collection),
  					    parser->device->collection_size,
  					    2),
  				GFP_KERNEL);
  		if (collection == NULL) {
  			hid_err(parser->device, "failed to reallocate collection array\n");
  			return -ENOMEM;
  		}
  		memcpy(collection, parser->device->collection,
  			sizeof(struct hid_collection) *
  			parser->device->collection_size);
  		memset(collection + parser->device->collection_size, 0,
  			sizeof(struct hid_collection) *
  			parser->device->collection_size);
  		kfree(parser->device->collection);
  		parser->device->collection = collection;
  		parser->device->collection_size *= 2;
  	}
  
  	parser->collection_stack[parser->collection_stack_ptr++] =
  		parser->device->maxcollection;
  
  	collection_index = parser->device->maxcollection++;
  	collection = parser->device->collection + collection_index;
  	collection->type = type;
  	collection->usage = usage;
  	collection->level = parser->collection_stack_ptr - 1;
  	collection->parent_idx = (collection->level == 0) ? -1 :
  		parser->collection_stack[collection->level - 1];
  
  	if (type == HID_COLLECTION_APPLICATION)
  		parser->device->maxapplication++;
  
  	return 0;
  }
  
  /*
   * Close a collection.
   */
  
  static int close_collection(struct hid_parser *parser)
  {
  	if (!parser->collection_stack_ptr) {
  		hid_err(parser->device, "collection stack underflow\n");
  		return -EINVAL;
  	}
  	parser->collection_stack_ptr--;
  	return 0;
  }
  
  /*
   * Climb up the stack, search for the specified collection type
   * and return the usage.
   */
  
  static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
  {
  	struct hid_collection *collection = parser->device->collection;
  	int n;
  
  	for (n = parser->collection_stack_ptr - 1; n >= 0; n--) {
  		unsigned index = parser->collection_stack[n];
  		if (collection[index].type == type)
  			return collection[index].usage;
  	}
  	return 0; /* we know nothing about this usage type */
  }
  
  /*
   * Concatenate usage which defines 16 bits or less with the
   * currently defined usage page to form a 32 bit usage
   */
  
  static void complete_usage(struct hid_parser *parser, unsigned int index)
  {
  	parser->local.usage[index] &= 0xFFFF;
  	parser->local.usage[index] |=
  		(parser->global.usage_page & 0xFFFF) << 16;
  }
  
  /*
   * Add a usage to the temporary parser table.
   */
  
  static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
  {
  	if (parser->local.usage_index >= HID_MAX_USAGES) {
  		hid_err(parser->device, "usage index exceeded\n");
  		return -1;
  	}
  	parser->local.usage[parser->local.usage_index] = usage;
  
  	/*
  	 * If Usage item only includes usage id, concatenate it with
  	 * currently defined usage page
  	 */
  	if (size <= 2)
  		complete_usage(parser, parser->local.usage_index);
  
  	parser->local.usage_size[parser->local.usage_index] = size;
  	parser->local.collection_index[parser->local.usage_index] =
  		parser->collection_stack_ptr ?
  		parser->collection_stack[parser->collection_stack_ptr - 1] : 0;
  	parser->local.usage_index++;
  	return 0;
  }
  
  /*
   * Register a new field for this report.
   */
  
  static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsigned flags)
  {
  	struct hid_report *report;
  	struct hid_field *field;
  	unsigned int usages;
  	unsigned int offset;
  	unsigned int i;
  	unsigned int application;
  
  	application = hid_lookup_collection(parser, HID_COLLECTION_APPLICATION);
  
  	report = hid_register_report(parser->device, report_type,
  				     parser->global.report_id, application);
  	if (!report) {
  		hid_err(parser->device, "hid_register_report failed\n");
  		return -1;
  	}
  
  	/* Handle both signed and unsigned cases properly */
  	if ((parser->global.logical_minimum < 0 &&
  		parser->global.logical_maximum <
  		parser->global.logical_minimum) ||
  		(parser->global.logical_minimum >= 0 &&
  		(__u32)parser->global.logical_maximum <
  		(__u32)parser->global.logical_minimum)) {
  		dbg_hid("logical range invalid 0x%x 0x%x\n",
  			parser->global.logical_minimum,
  			parser->global.logical_maximum);
  		return -1;
  	}
  
  	offset = report->size;
  	report->size += parser->global.report_size * parser->global.report_count;
  
  	/* Total size check: Allow for possible report index byte */
  	if (report->size > (HID_MAX_BUFFER_SIZE - 1) << 3) {
  		hid_err(parser->device, "report is too long\n");
  		return -1;
  	}
  
  	if (!parser->local.usage_index) /* Ignore padding fields */
  		return 0;
  
  	usages = max_t(unsigned, parser->local.usage_index,
  				 parser->global.report_count);
  
  	field = hid_register_field(report, usages, parser->global.report_count);
  	if (!field)
  		return 0;
  
  	field->physical = hid_lookup_collection(parser, HID_COLLECTION_PHYSICAL);
  	field->logical = hid_lookup_collection(parser, HID_COLLECTION_LOGICAL);
  	field->application = application;
  
  	for (i = 0; i < usages; i++) {
  		unsigned j = i;
  		/* Duplicate the last usage we parsed if we have excess values */
  		if (i >= parser->local.usage_index)
  			j = parser->local.usage_index - 1;
  		field->usage[i].hid = parser->local.usage[j];
  		field->usage[i].collection_index =
  			parser->local.collection_index[j];
  		field->usage[i].usage_index = i;
  		field->usage[i].resolution_multiplier = 1;
  	}
  
  	field->maxusage = usages;
  	field->flags = flags;
  	field->report_offset = offset;
  	field->report_type = report_type;
  	field->report_size = parser->global.report_size;
  	field->report_count = parser->global.report_count;
  	field->logical_minimum = parser->global.logical_minimum;
  	field->logical_maximum = parser->global.logical_maximum;
  	field->physical_minimum = parser->global.physical_minimum;
  	field->physical_maximum = parser->global.physical_maximum;
  	field->unit_exponent = parser->global.unit_exponent;
  	field->unit = parser->global.unit;
  
  	return 0;
  }
  
  /*
   * Read data value from item.
   */
  
  static u32 item_udata(struct hid_item *item)
  {
  	switch (item->size) {
  	case 1: return item->data.u8;
  	case 2: return item->data.u16;
  	case 4: return item->data.u32;
  	}
  	return 0;
  }
  
  static s32 item_sdata(struct hid_item *item)
  {
  	switch (item->size) {
  	case 1: return item->data.s8;
  	case 2: return item->data.s16;
  	case 4: return item->data.s32;
  	}
  	return 0;
  }
  
  /*
   * Process a global item.
   */
  
  static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
  {
  	__s32 raw_value;
  	switch (item->tag) {
  	case HID_GLOBAL_ITEM_TAG_PUSH:
  
  		if (parser->global_stack_ptr == HID_GLOBAL_STACK_SIZE) {
  			hid_err(parser->device, "global environment stack overflow\n");
  			return -1;
  		}
  
  		memcpy(parser->global_stack + parser->global_stack_ptr++,
  			&parser->global, sizeof(struct hid_global));
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_POP:
  
  		if (!parser->global_stack_ptr) {
  			hid_err(parser->device, "global environment stack underflow\n");
  			return -1;
  		}
  
  		memcpy(&parser->global, parser->global_stack +
  			--parser->global_stack_ptr, sizeof(struct hid_global));
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_USAGE_PAGE:
  		parser->global.usage_page = item_udata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_LOGICAL_MINIMUM:
  		parser->global.logical_minimum = item_sdata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_LOGICAL_MAXIMUM:
  		if (parser->global.logical_minimum < 0)
  			parser->global.logical_maximum = item_sdata(item);
  		else
  			parser->global.logical_maximum = item_udata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_PHYSICAL_MINIMUM:
  		parser->global.physical_minimum = item_sdata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_PHYSICAL_MAXIMUM:
  		if (parser->global.physical_minimum < 0)
  			parser->global.physical_maximum = item_sdata(item);
  		else
  			parser->global.physical_maximum = item_udata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT:
  		/* Many devices provide unit exponent as a two's complement
  		 * nibble due to the common misunderstanding of HID
  		 * specification 1.11, 6.2.2.7 Global Items. Attempt to handle
  		 * both this and the standard encoding. */
  		raw_value = item_sdata(item);
  		if (!(raw_value & 0xfffffff0))
  			parser->global.unit_exponent = hid_snto32(raw_value, 4);
  		else
  			parser->global.unit_exponent = raw_value;
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_UNIT:
  		parser->global.unit = item_udata(item);
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_REPORT_SIZE:
  		parser->global.report_size = item_udata(item);
  		if (parser->global.report_size > 256) {
  			hid_err(parser->device, "invalid report_size %d\n",
  					parser->global.report_size);
  			return -1;
  		}
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_REPORT_COUNT:
  		parser->global.report_count = item_udata(item);
  		if (parser->global.report_count > HID_MAX_USAGES) {
  			hid_err(parser->device, "invalid report_count %d\n",
  					parser->global.report_count);
  			return -1;
  		}
  		return 0;
  
  	case HID_GLOBAL_ITEM_TAG_REPORT_ID:
  		parser->global.report_id = item_udata(item);
  		if (parser->global.report_id == 0 ||
  		    parser->global.report_id >= HID_MAX_IDS) {
  			hid_err(parser->device, "report_id %u is invalid\n",
  				parser->global.report_id);
  			return -1;
  		}
  		return 0;
  
  	default:
  		hid_err(parser->device, "unknown global tag 0x%x\n", item->tag);
  		return -1;
  	}
  }
  
  /*
   * Process a local item.
   */
  
  static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  {
  	__u32 data;
  	unsigned n;
  	__u32 count;
  
  	data = item_udata(item);
  
  	switch (item->tag) {
  	case HID_LOCAL_ITEM_TAG_DELIMITER:
  
  		if (data) {
  			/*
  			 * We treat items before the first delimiter
  			 * as global to all usage sets (branch 0).
  			 * In the moment we process only these global
  			 * items and the first delimiter set.
  			 */
  			if (parser->local.delimiter_depth != 0) {
  				hid_err(parser->device, "nested delimiters\n");
  				return -1;
  			}
  			parser->local.delimiter_depth++;
  			parser->local.delimiter_branch++;
  		} else {
  			if (parser->local.delimiter_depth < 1) {
  				hid_err(parser->device, "bogus close delimiter\n");
  				return -1;
  			}
  			parser->local.delimiter_depth--;
  		}
  		return 0;
  
  	case HID_LOCAL_ITEM_TAG_USAGE:
  
  		if (parser->local.delimiter_branch > 1) {
  			dbg_hid("alternative usage ignored\n");
  			return 0;
  		}
  
  		return hid_add_usage(parser, data, item->size);
  
  	case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:
  
  		if (parser->local.delimiter_branch > 1) {
  			dbg_hid("alternative usage ignored\n");
  			return 0;
  		}
  
  		parser->local.usage_minimum = data;
  		return 0;
  
  	case HID_LOCAL_ITEM_TAG_USAGE_MAXIMUM:
  
  		if (parser->local.delimiter_branch > 1) {
  			dbg_hid("alternative usage ignored\n");
  			return 0;
  		}
  
  		count = data - parser->local.usage_minimum;
  		if (count + parser->local.usage_index >= HID_MAX_USAGES) {
  			/*
  			 * We do not warn if the name is not set, we are
  			 * actually pre-scanning the device.
  			 */
  			if (dev_name(&parser->device->dev))
  				hid_warn(parser->device,
  					 "ignoring exceeding usage max\n");
  			data = HID_MAX_USAGES - parser->local.usage_index +
  				parser->local.usage_minimum - 1;
  			if (data <= 0) {
  				hid_err(parser->device,
  					"no more usage index available\n");
  				return -1;
  			}
  		}
  
  		for (n = parser->local.usage_minimum; n <= data; n++)
  			if (hid_add_usage(parser, n, item->size)) {
  				dbg_hid("hid_add_usage failed\n");
  				return -1;
  			}
  		return 0;
  
  	default:
  
  		dbg_hid("unknown local item tag 0x%x\n", item->tag);
  		return 0;
  	}
  	return 0;
  }
  
  /*
   * Concatenate Usage Pages into Usages where relevant:
   * As per specification, 6.2.2.8: "When the parser encounters a main item it
   * concatenates the last declared Usage Page with a Usage to form a complete
   * usage value."
   */
  
  static void hid_concatenate_last_usage_page(struct hid_parser *parser)
  {
  	int i;
  	unsigned int usage_page;
  	unsigned int current_page;
  
  	if (!parser->local.usage_index)
  		return;
  
  	usage_page = parser->global.usage_page;
  
  	/*
  	 * Concatenate usage page again only if last declared Usage Page
  	 * has not been already used in previous usages concatenation
  	 */
  	for (i = parser->local.usage_index - 1; i >= 0; i--) {
  		if (parser->local.usage_size[i] > 2)
  			/* Ignore extended usages */
  			continue;
  
  		current_page = parser->local.usage[i] >> 16;
  		if (current_page == usage_page)
  			break;
  
  		complete_usage(parser, i);
  	}
  }
  
  /*
   * Process a main item.
   */
  
  static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
  {
  	__u32 data;
  	int ret;
  
  	hid_concatenate_last_usage_page(parser);
  
  	data = item_udata(item);
  
  	switch (item->tag) {
  	case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
  		ret = open_collection(parser, data & 0xff);
  		break;
  	case HID_MAIN_ITEM_TAG_END_COLLECTION:
  		ret = close_collection(parser);
  		break;
  	case HID_MAIN_ITEM_TAG_INPUT:
  		ret = hid_add_field(parser, HID_INPUT_REPORT, data);
  		break;
  	case HID_MAIN_ITEM_TAG_OUTPUT:
  		ret = hid_add_field(parser, HID_OUTPUT_REPORT, data);
  		break;
  	case HID_MAIN_ITEM_TAG_FEATURE:
  		ret = hid_add_field(parser, HID_FEATURE_REPORT, data);
  		break;
  	default:
  		hid_warn(parser->device, "unknown main item tag 0x%x\n", item->tag);
  		ret = 0;
  	}
  
  	memset(&parser->local, 0, sizeof(parser->local));	/* Reset the local parser environment */
  
  	return ret;
  }
  
  /*
   * Process a reserved item.
   */
  
  static int hid_parser_reserved(struct hid_parser *parser, struct hid_item *item)
  {
  	dbg_hid("reserved item type, tag 0x%x\n", item->tag);
  	return 0;
  }
  
  /*
   * Free a report and all registered fields. The field->usage and
   * field->value table's are allocated behind the field, so we need
   * only to free(field) itself.
   */
  
  static void hid_free_report(struct hid_report *report)
  {
  	unsigned n;
  
  	for (n = 0; n < report->maxfield; n++)
  		kfree(report->field[n]);
  	kfree(report);
  }
  
  /*
   * Close report. This function returns the device
   * state to the point prior to hid_open_report().
   */
  static void hid_close_report(struct hid_device *device)
  {
  	unsigned i, j;
  
  	for (i = 0; i < HID_REPORT_TYPES; i++) {
  		struct hid_report_enum *report_enum = device->report_enum + i;
  
  		for (j = 0; j < HID_MAX_IDS; j++) {
  			struct hid_report *report = report_enum->report_id_hash[j];
  			if (report)
  				hid_free_report(report);
  		}
  		memset(report_enum, 0, sizeof(*report_enum));
  		INIT_LIST_HEAD(&report_enum->report_list);
  	}
  
  	kfree(device->rdesc);
  	device->rdesc = NULL;
  	device->rsize = 0;
  
  	kfree(device->collection);
  	device->collection = NULL;
  	device->collection_size = 0;
  	device->maxcollection = 0;
  	device->maxapplication = 0;
  
  	device->status &= ~HID_STAT_PARSED;
  }
  
  /*
   * Free a device structure, all reports, and all fields.
   */
  
  static void hid_device_release(struct device *dev)
  {
  	struct hid_device *hid = to_hid_device(dev);
  
  	hid_close_report(hid);
  	kfree(hid->dev_rdesc);
  	kfree(hid);
  }
  
  /*
   * Fetch a report description item from the data stream. We support long
   * items, though they are not used yet.
   */
  
  static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
  {
  	u8 b;
  
  	if ((end - start) <= 0)
  		return NULL;
  
  	b = *start++;
  
  	item->type = (b >> 2) & 3;
  	item->tag  = (b >> 4) & 15;
  
  	if (item->tag == HID_ITEM_TAG_LONG) {
  
  		item->format = HID_ITEM_FORMAT_LONG;
  
  		if ((end - start) < 2)
  			return NULL;
  
  		item->size = *start++;
  		item->tag  = *start++;
  
  		if ((end - start) < item->size)
  			return NULL;
  
  		item->data.longdata = start;
  		start += item->size;
  		return start;
  	}
  
  	item->format = HID_ITEM_FORMAT_SHORT;
  	item->size = b & 3;
  
  	switch (item->size) {
  	case 0:
  		return start;
  
  	case 1:
  		if ((end - start) < 1)
  			return NULL;
  		item->data.u8 = *start++;
  		return start;
  
  	case 2:
  		if ((end - start) < 2)
  			return NULL;
  		item->data.u16 = get_unaligned_le16(start);
  		start = (__u8 *)((__le16 *)start + 1);
  		return start;
  
  	case 3:
  		item->size++;
  		if ((end - start) < 4)
  			return NULL;
  		item->data.u32 = get_unaligned_le32(start);
  		start = (__u8 *)((__le32 *)start + 1);
  		return start;
  	}
  
  	return NULL;
  }
  
  static void hid_scan_input_usage(struct hid_parser *parser, u32 usage)
  {
  	struct hid_device *hid = parser->device;
  
  	if (usage == HID_DG_CONTACTID)
  		hid->group = HID_GROUP_MULTITOUCH;
  }
  
  static void hid_scan_feature_usage(struct hid_parser *parser, u32 usage)
  {
  	if (usage == 0xff0000c5 && parser->global.report_count == 256 &&
  	    parser->global.report_size == 8)
  		parser->scan_flags |= HID_SCAN_FLAG_MT_WIN_8;
  
  	if (usage == 0xff0000c6 && parser->global.report_count == 1 &&
  	    parser->global.report_size == 8)
  		parser->scan_flags |= HID_SCAN_FLAG_MT_WIN_8;
  }
  
  static void hid_scan_collection(struct hid_parser *parser, unsigned type)
  {
  	struct hid_device *hid = parser->device;
  	int i;
  
  	if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&
  	    type == HID_COLLECTION_PHYSICAL)
  		hid->group = HID_GROUP_SENSOR_HUB;
  
  	if (hid->vendor == USB_VENDOR_ID_MICROSOFT &&
  	    hid->product == USB_DEVICE_ID_MS_POWER_COVER &&
  	    hid->group == HID_GROUP_MULTITOUCH)
  		hid->group = HID_GROUP_GENERIC;
  
  	if ((parser->global.usage_page << 16) == HID_UP_GENDESK)
  		for (i = 0; i < parser->local.usage_index; i++)
  			if (parser->local.usage[i] == HID_GD_POINTER)
  				parser->scan_flags |= HID_SCAN_FLAG_GD_POINTER;
  
  	if ((parser->global.usage_page << 16) >= HID_UP_MSVENDOR)
  		parser->scan_flags |= HID_SCAN_FLAG_VENDOR_SPECIFIC;
  }
  
  static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
  {
  	__u32 data;
  	int i;
  
  	hid_concatenate_last_usage_page(parser);
  
  	data = item_udata(item);
  
  	switch (item->tag) {
  	case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
  		hid_scan_collection(parser, data & 0xff);
  		break;
  	case HID_MAIN_ITEM_TAG_END_COLLECTION:
  		break;
  	case HID_MAIN_ITEM_TAG_INPUT:
  		/* ignore constant inputs, they will be ignored by hid-input */
  		if (data & HID_MAIN_ITEM_CONSTANT)
  			break;
  		for (i = 0; i < parser->local.usage_index; i++)
  			hid_scan_input_usage(parser, parser->local.usage[i]);
  		break;
  	case HID_MAIN_ITEM_TAG_OUTPUT:
  		break;
  	case HID_MAIN_ITEM_TAG_FEATURE:
  		for (i = 0; i < parser->local.usage_index; i++)
  			hid_scan_feature_usage(parser, parser->local.usage[i]);
  		break;
  	}
  
  	/* Reset the local parser environment */
  	memset(&parser->local, 0, sizeof(parser->local));
  
  	return 0;
  }
  
  /*
   * Scan a report descriptor before the device is added to the bus.
   * Sets device groups and other properties that determine what driver
   * to load.
   */
  static int hid_scan_report(struct hid_device *hid)
  {
  	struct hid_parser *parser;
  	struct hid_item item;
  	__u8 *start = hid->dev_rdesc;
  	__u8 *end = start + hid->dev_rsize;
  	static int (*dispatch_type[])(struct hid_parser *parser,
  				      struct hid_item *item) = {
  		hid_scan_main,
  		hid_parser_global,
  		hid_parser_local,
  		hid_parser_reserved
  	};
  
  	parser = vzalloc(sizeof(struct hid_parser));
  	if (!parser)
  		return -ENOMEM;
  
  	parser->device = hid;
  	hid->group = HID_GROUP_GENERIC;
  
  	/*
  	 * The parsing is simpler than the one in hid_open_report() as we should
  	 * be robust against hid errors. Those errors will be raised by
  	 * hid_open_report() anyway.
  	 */
  	while ((start = fetch_item(start, end, &item)) != NULL)
  		dispatch_type[item.type](parser, &item);
  
  	/*
  	 * Handle special flags set during scanning.
  	 */
  	if ((parser->scan_flags & HID_SCAN_FLAG_MT_WIN_8) &&
  	    (hid->group == HID_GROUP_MULTITOUCH))
  		hid->group = HID_GROUP_MULTITOUCH_WIN_8;
  
  	/*
  	 * Vendor specific handlings
  	 */
  	switch (hid->vendor) {
  	case USB_VENDOR_ID_WACOM:
  		hid->group = HID_GROUP_WACOM;
  		break;
  	case USB_VENDOR_ID_SYNAPTICS:
  		if (hid->group == HID_GROUP_GENERIC)
  			if ((parser->scan_flags & HID_SCAN_FLAG_VENDOR_SPECIFIC)
  			    && (parser->scan_flags & HID_SCAN_FLAG_GD_POINTER))
  				/*
  				 * hid-rmi should take care of them,
  				 * not hid-generic
  				 */
  				hid->group = HID_GROUP_RMI;
  		break;
  	}
  
  	kfree(parser->collection_stack);
  	vfree(parser);
  	return 0;
  }
  
  /**
   * hid_parse_report - parse device report
   *
   * @device: hid device
   * @start: report start
   * @size: report size
   *
   * Allocate the device report as read by the bus driver. This function should
   * only be called from parse() in ll drivers.
   */
  int hid_parse_report(struct hid_device *hid, __u8 *start, unsigned size)
  {
  	hid->dev_rdesc = kmemdup(start, size, GFP_KERNEL);
  	if (!hid->dev_rdesc)
  		return -ENOMEM;
  	hid->dev_rsize = size;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(hid_parse_report);
  
  static const char * const hid_report_names[] = {
  	"HID_INPUT_REPORT",
  	"HID_OUTPUT_REPORT",
  	"HID_FEATURE_REPORT",
  };
  /**
   * hid_validate_values - validate existing device report's value indexes
   *
   * @device: hid device
   * @type: which report type to examine
   * @id: which report ID to examine (0 for first)
   * @field_index: which report field to examine
   * @report_counts: expected number of values
   *
   * Validate the number of values in a given field of a given report, after
   * parsing.
   */
  struct hid_report *hid_validate_values(struct hid_device *hid,
  				       unsigned int type, unsigned int id,
  				       unsigned int field_index,
  				       unsigned int report_counts)
  {
  	struct hid_report *report;
  
  	if (type > HID_FEATURE_REPORT) {
  		hid_err(hid, "invalid HID report type %u\n", type);
  		return NULL;
  	}
  
  	if (id >= HID_MAX_IDS) {
  		hid_err(hid, "invalid HID report id %u\n", id);
  		return NULL;
  	}
  
  	/*
  	 * Explicitly not using hid_get_report() here since it depends on
  	 * ->numbered being checked, which may not always be the case when
  	 * drivers go to access report values.
  	 */
  	if (id == 0) {
  		/*
  		 * Validating on id 0 means we should examine the first
  		 * report in the list.
  		 */
  		report = list_entry(
  				hid->report_enum[type].report_list.next,
  				struct hid_report, list);
  	} else {
  		report = hid->report_enum[type].report_id_hash[id];
  	}
  	if (!report) {
  		hid_err(hid, "missing %s %u\n", hid_report_names[type], id);
  		return NULL;
  	}
  	if (report->maxfield <= field_index) {
  		hid_err(hid, "not enough fields in %s %u\n",
  			hid_report_names[type], id);
  		return NULL;
  	}
  	if (report->field[field_index]->report_count < report_counts) {
  		hid_err(hid, "not enough values in %s %u field %u\n",
  			hid_report_names[type], id, field_index);
  		return NULL;
  	}
  	return report;
  }
  EXPORT_SYMBOL_GPL(hid_validate_values);
  
  static int hid_calculate_multiplier(struct hid_device *hid,
  				     struct hid_field *multiplier)
  {
  	int m;
  	__s32 v = *multiplier->value;
  	__s32 lmin = multiplier->logical_minimum;
  	__s32 lmax = multiplier->logical_maximum;
  	__s32 pmin = multiplier->physical_minimum;
  	__s32 pmax = multiplier->physical_maximum;
  
  	/*
  	 * "Because OS implementations will generally divide the control's
  	 * reported count by the Effective Resolution Multiplier, designers
  	 * should take care not to establish a potential Effective
  	 * Resolution Multiplier of zero."
  	 * HID Usage Table, v1.12, Section 4.3.1, p31
  	 */
  	if (lmax - lmin == 0)
  		return 1;
  	/*
  	 * Handling the unit exponent is left as an exercise to whoever
  	 * finds a device where that exponent is not 0.
  	 */
  	m = ((v - lmin)/(lmax - lmin) * (pmax - pmin) + pmin);
  	if (unlikely(multiplier->unit_exponent != 0)) {
  		hid_warn(hid,
  			 "unsupported Resolution Multiplier unit exponent %d\n",
  			 multiplier->unit_exponent);
  	}
  
  	/* There are no devices with an effective multiplier > 255 */
  	if (unlikely(m == 0 || m > 255 || m < -255)) {
  		hid_warn(hid, "unsupported Resolution Multiplier %d\n", m);
  		m = 1;
  	}
  
  	return m;
  }
  
  static void hid_apply_multiplier_to_field(struct hid_device *hid,
  					  struct hid_field *field,
  					  struct hid_collection *multiplier_collection,
  					  int effective_multiplier)
  {
  	struct hid_collection *collection;
  	struct hid_usage *usage;
  	int i;
  
  	/*
  	 * If multiplier_collection is NULL, the multiplier applies
  	 * to all fields in the report.
  	 * Otherwise, it is the Logical Collection the multiplier applies to
  	 * but our field may be in a subcollection of that collection.
  	 */
  	for (i = 0; i < field->maxusage; i++) {
  		usage = &field->usage[i];
  
  		collection = &hid->collection[usage->collection_index];
  		while (collection->parent_idx != -1 &&
  		       collection != multiplier_collection)
  			collection = &hid->collection[collection->parent_idx];
  
  		if (collection->parent_idx != -1 ||
  		    multiplier_collection == NULL)
  			usage->resolution_multiplier = effective_multiplier;
  
  	}
  }
  
  static void hid_apply_multiplier(struct hid_device *hid,
  				 struct hid_field *multiplier)
  {
  	struct hid_report_enum *rep_enum;
  	struct hid_report *rep;
  	struct hid_field *field;
  	struct hid_collection *multiplier_collection;
  	int effective_multiplier;
  	int i;
  
  	/*
  	 * "The Resolution Multiplier control must be contained in the same
  	 * Logical Collection as the control(s) to which it is to be applied.
  	 * If no Resolution Multiplier is defined, then the Resolution
  	 * Multiplier defaults to 1.  If more than one control exists in a
  	 * Logical Collection, the Resolution Multiplier is associated with
  	 * all controls in the collection. If no Logical Collection is
  	 * defined, the Resolution Multiplier is associated with all
  	 * controls in the report."
  	 * HID Usage Table, v1.12, Section 4.3.1, p30
  	 *
  	 * Thus, search from the current collection upwards until we find a
  	 * logical collection. Then search all fields for that same parent
  	 * collection. Those are the fields the multiplier applies to.
  	 *
  	 * If we have more than one multiplier, it will overwrite the
  	 * applicable fields later.
  	 */
  	multiplier_collection = &hid->collection[multiplier->usage->collection_index];
  	while (multiplier_collection->parent_idx != -1 &&
  	       multiplier_collection->type != HID_COLLECTION_LOGICAL)
  		multiplier_collection = &hid->collection[multiplier_collection->parent_idx];
  
  	effective_multiplier = hid_calculate_multiplier(hid, multiplier);
  
  	rep_enum = &hid->report_enum[HID_INPUT_REPORT];
  	list_for_each_entry(rep, &rep_enum->report_list, list) {
  		for (i = 0; i < rep->maxfield; i++) {
  			field = rep->field[i];
  			hid_apply_multiplier_to_field(hid, field,
  						      multiplier_collection,
  						      effective_multiplier);
  		}
  	}
  }
  
  /*
   * hid_setup_resolution_multiplier - set up all resolution multipliers
   *
   * @device: hid device
   *
   * Search for all Resolution Multiplier Feature Reports and apply their
   * value to all matching Input items. This only updates the internal struct
   * fields.
   *
   * The Resolution Multiplier is applied by the hardware. If the multiplier
   * is anything other than 1, the hardware will send pre-multiplied events
   * so that the same physical interaction generates an accumulated
   *	accumulated_value = value * * multiplier
   * This may be achieved by sending
   * - "value * multiplier" for each event, or
   * - "value" but "multiplier" times as frequently, or
   * - a combination of the above
   * The only guarantee is that the same physical interaction always generates
   * an accumulated 'value * multiplier'.
   *
   * This function must be called before any event processing and after
   * any SetRequest to the Resolution Multiplier.
   */
  void hid_setup_resolution_multiplier(struct hid_device *hid)
  {
  	struct hid_report_enum *rep_enum;
  	struct hid_report *rep;
  	struct hid_usage *usage;
  	int i, j;
  
  	rep_enum = &hid->report_enum[HID_FEATURE_REPORT];
  	list_for_each_entry(rep, &rep_enum->report_list, list) {
  		for (i = 0; i < rep->maxfield; i++) {
  			/* Ignore if report count is out of bounds. */
  			if (rep->field[i]->report_count < 1)
  				continue;
  
  			for (j = 0; j < rep->field[i]->maxusage; j++) {
  				usage = &rep->field[i]->usage[j];
  				if (usage->hid == HID_GD_RESOLUTION_MULTIPLIER)
  					hid_apply_multiplier(hid,
  							     rep->field[i]);
  			}
  		}
  	}
  }
  EXPORT_SYMBOL_GPL(hid_setup_resolution_multiplier);
  
  /**
   * hid_open_report - open a driver-specific device report
   *
   * @device: hid device
   *
   * Parse a report description into a hid_device structure. Reports are
   * enumerated, fields are attached to these reports.
   * 0 returned on success, otherwise nonzero error value.
   *
   * This function (or the equivalent hid_parse() macro) should only be
   * called from probe() in drivers, before starting the device.
   */
  int hid_open_report(struct hid_device *device)
  {
  	struct hid_parser *parser;
  	struct hid_item item;
  	unsigned int size;
  	__u8 *start;
  	__u8 *buf;
  	__u8 *end;
  	__u8 *next;
  	int ret;
  	static int (*dispatch_type[])(struct hid_parser *parser,
  				      struct hid_item *item) = {
  		hid_parser_main,
  		hid_parser_global,
  		hid_parser_local,
  		hid_parser_reserved
  	};
  
  	if (WARN_ON(device->status & HID_STAT_PARSED))
  		return -EBUSY;
  
  	start = device->dev_rdesc;
  	if (WARN_ON(!start))
  		return -ENODEV;
  	size = device->dev_rsize;
  
  	buf = kmemdup(start, size, GFP_KERNEL);
  	if (buf == NULL)
  		return -ENOMEM;
  
  	if (device->driver->report_fixup)
  		start = device->driver->report_fixup(device, buf, &size);
  	else
  		start = buf;
  
  	start = kmemdup(start, size, GFP_KERNEL);
  	kfree(buf);
  	if (start == NULL)
  		return -ENOMEM;
  
  	device->rdesc = start;
  	device->rsize = size;
  
  	parser = vzalloc(sizeof(struct hid_parser));
  	if (!parser) {
  		ret = -ENOMEM;
  		goto alloc_err;
  	}
  
  	parser->device = device;
  
  	end = start + size;
  
  	device->collection = kcalloc(HID_DEFAULT_NUM_COLLECTIONS,
  				     sizeof(struct hid_collection), GFP_KERNEL);
  	if (!device->collection) {
  		ret = -ENOMEM;
  		goto err;
  	}
  	device->collection_size = HID_DEFAULT_NUM_COLLECTIONS;
  
  	ret = -EINVAL;
  	while ((next = fetch_item(start, end, &item)) != NULL) {
  		start = next;
  
  		if (item.format != HID_ITEM_FORMAT_SHORT) {
  			hid_err(device, "unexpected long global item\n");
  			goto err;
  		}
  
  		if (dispatch_type[item.type](parser, &item)) {
  			hid_err(device, "item %u %u %u %u parsing failed\n",
  				item.format, (unsigned)item.size,
  				(unsigned)item.type, (unsigned)item.tag);
  			goto err;
  		}
  
  		if (start == end) {
  			if (parser->collection_stack_ptr) {
  				hid_err(device, "unbalanced collection at end of report description\n");
  				goto err;
  			}
  			if (parser->local.delimiter_depth) {
  				hid_err(device, "unbalanced delimiter at end of report description\n");
  				goto err;
  			}
  
  			/*
  			 * fetch initial values in case the device's
  			 * default multiplier isn't the recommended 1
  			 */
  			hid_setup_resolution_multiplier(device);
  
  			kfree(parser->collection_stack);
  			vfree(parser);
  			device->status |= HID_STAT_PARSED;
  
  			return 0;
  		}
  	}
  
  	hid_err(device, "item fetching failed at offset %u/%u\n",
  		size - (unsigned int)(end - start), size);
  err:
  	kfree(parser->collection_stack);
  alloc_err:
  	vfree(parser);
  	hid_close_report(device);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(hid_open_report);
  
  /*
   * Convert a signed n-bit integer to signed 32-bit integer. Common
   * cases are done through the compiler, the screwed things has to be
   * done by hand.
   */
  
  static s32 snto32(__u32 value, unsigned n)
  {
  	switch (n) {
  	case 8:  return ((__s8)value);
  	case 16: return ((__s16)value);
  	case 32: return ((__s32)value);
  	}
  	return value & (1 << (n - 1)) ? value | (~0U << n) : value;
  }
  
  s32 hid_snto32(__u32 value, unsigned n)
  {
  	return snto32(value, n);
  }
  EXPORT_SYMBOL_GPL(hid_snto32);
  
  /*
   * Convert a signed 32-bit integer to a signed n-bit integer.
   */
  
  static u32 s32ton(__s32 value, unsigned n)
  {
  	s32 a = value >> (n - 1);
  	if (a && a != -1)
  		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
  	return value & ((1 << n) - 1);
  }
  
  /*
   * Extract/implement a data field from/to a little endian report (bit array).
   *
   * Code sort-of follows HID spec:
   *     http://www.usb.org/developers/hidpage/HID1_11.pdf
   *
   * While the USB HID spec allows unlimited length bit fields in "report
   * descriptors", most devices never use more than 16 bits.
   * One model of UPS is claimed to report "LINEV" as a 32-bit field.
   * Search linux-kernel and linux-usb-devel archives for "hid-core extract".
   */
  
  static u32 __extract(u8 *report, unsigned offset, int n)
  {
  	unsigned int idx = offset / 8;
  	unsigned int bit_nr = 0;
  	unsigned int bit_shift = offset % 8;
  	int bits_to_copy = 8 - bit_shift;
  	u32 value = 0;
  	u32 mask = n < 32 ? (1U << n) - 1 : ~0U;
  
  	while (n > 0) {
  		value |= ((u32)report[idx] >> bit_shift) << bit_nr;
  		n -= bits_to_copy;
  		bit_nr += bits_to_copy;
  		bits_to_copy = 8;
  		bit_shift = 0;
  		idx++;
  	}
  
  	return value & mask;
  }
  
  u32 hid_field_extract(const struct hid_device *hid, u8 *report,
  			unsigned offset, unsigned n)
  {
  	if (n > 32) {
  		hid_warn_once(hid, "%s() called with n (%d) > 32! (%s)\n",
  			      __func__, n, current->comm);
  		n = 32;
  	}
  
  	return __extract(report, offset, n);
  }
  EXPORT_SYMBOL_GPL(hid_field_extract);
  
  /*
   * "implement" : set bits in a little endian bit stream.
   * Same concepts as "extract" (see comments above).
   * The data mangled in the bit stream remains in little endian
   * order the whole time. It make more sense to talk about
   * endianness of register values by considering a register
   * a "cached" copy of the little endian bit stream.
   */
  
  static void __implement(u8 *report, unsigned offset, int n, u32 value)
  {
  	unsigned int idx = offset / 8;
  	unsigned int bit_shift = offset % 8;
  	int bits_to_set = 8 - bit_shift;
  
  	while (n - bits_to_set >= 0) {
  		report[idx] &= ~(0xff << bit_shift);
  		report[idx] |= value << bit_shift;
  		value >>= bits_to_set;
  		n -= bits_to_set;
  		bits_to_set = 8;
  		bit_shift = 0;
  		idx++;
  	}
  
  	/* last nibble */
  	if (n) {
  		u8 bit_mask = ((1U << n) - 1);
  		report[idx] &= ~(bit_mask << bit_shift);
  		report[idx] |= value << bit_shift;
  	}
  }
  
  static void implement(const struct hid_device *hid, u8 *report,
  		      unsigned offset, unsigned n, u32 value)
  {
  	if (unlikely(n > 32)) {
  		hid_warn(hid, "%s() called with n (%d) > 32! (%s)\n",
  			 __func__, n, current->comm);
  		n = 32;
  	} else if (n < 32) {
  		u32 m = (1U << n) - 1;
  
  		if (unlikely(value > m)) {
  			hid_warn(hid,
  				 "%s() called with too large value %d (n: %d)! (%s)\n",
  				 __func__, value, n, current->comm);
  			WARN_ON(1);
  			value &= m;
  		}
  	}
  
  	__implement(report, offset, n, value);
  }
  
  /*
   * Search an array for a value.
   */
  
  static int search(__s32 *array, __s32 value, unsigned n)
  {
  	while (n--) {
  		if (*array++ == value)
  			return 0;
  	}
  	return -1;
  }
  
  /**
   * hid_match_report - check if driver's raw_event should be called
   *
   * @hid: hid device
   * @report_type: type to match against
   *
   * compare hid->driver->report_table->report_type to report->type
   */
  static int hid_match_report(struct hid_device *hid, struct hid_report *report)
  {
  	const struct hid_report_id *id = hid->driver->report_table;
  
  	if (!id) /* NULL means all */
  		return 1;
  
  	for (; id->report_type != HID_TERMINATOR; id++)
  		if (id->report_type == HID_ANY_ID ||
  				id->report_type == report->type)
  			return 1;
  	return 0;
  }
  
  /**
   * hid_match_usage - check if driver's event should be called
   *
   * @hid: hid device
   * @usage: usage to match against
   *
   * compare hid->driver->usage_table->usage_{type,code} to
   * usage->usage_{type,code}
   */
  static int hid_match_usage(struct hid_device *hid, struct hid_usage *usage)
  {
  	const struct hid_usage_id *id = hid->driver->usage_table;
  
  	if (!id) /* NULL means all */
  		return 1;
  
  	for (; id->usage_type != HID_ANY_ID - 1; id++)
  		if ((id->usage_hid == HID_ANY_ID ||
  				id->usage_hid == usage->hid) &&
  				(id->usage_type == HID_ANY_ID ||
  				id->usage_type == usage->type) &&
  				(id->usage_code == HID_ANY_ID ||
  				 id->usage_code == usage->code))
  			return 1;
  	return 0;
  }
  
  static void hid_process_event(struct hid_device *hid, struct hid_field *field,
  		struct hid_usage *usage, __s32 value, int interrupt)
  {
  	struct hid_driver *hdrv = hid->driver;
  	int ret;
  
  	if (!list_empty(&hid->debug_list))
  		hid_dump_input(hid, usage, value);
  
  	if (hdrv && hdrv->event && hid_match_usage(hid, usage)) {
  		ret = hdrv->event(hid, field, usage, value);
  		if (ret != 0) {
  			if (ret < 0)
  				hid_err(hid, "%s's event failed with %d\n",
  						hdrv->name, ret);
  			return;
  		}
  	}
  
  	if (hid->claimed & HID_CLAIMED_INPUT)
  		hidinput_hid_event(hid, field, usage, value);
  	if (hid->claimed & HID_CLAIMED_HIDDEV && interrupt && hid->hiddev_hid_event)
  		hid->hiddev_hid_event(hid, field, usage, value);
  }
  
  /*
   * Analyse a received field, and fetch the data from it. The field
   * content is stored for next report processing (we do differential
   * reporting to the layer).
   */
  
  static void hid_input_field(struct hid_device *hid, struct hid_field *field,
  			    __u8 *data, int interrupt)
  {
  	unsigned n;
  	unsigned count = field->report_count;
  	unsigned offset = field->report_offset;
  	unsigned size = field->report_size;
  	__s32 min = field->logical_minimum;
  	__s32 max = field->logical_maximum;
  	__s32 *value;
  
  	value = kmalloc_array(count, sizeof(__s32), GFP_ATOMIC);
  	if (!value)
  		return;
  
  	for (n = 0; n < count; n++) {
  
  		value[n] = min < 0 ?
  			snto32(hid_field_extract(hid, data, offset + n * size,
  			       size), size) :
  			hid_field_extract(hid, data, offset + n * size, size);
  
  		/* Ignore report if ErrorRollOver */
  		if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
  		    value[n] >= min && value[n] <= max &&
  		    value[n] - min < field->maxusage &&
  		    field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
  			goto exit;
  	}
  
  	for (n = 0; n < count; n++) {
  
  		if (HID_MAIN_ITEM_VARIABLE & field->flags) {
  			hid_process_event(hid, field, &field->usage[n], value[n], interrupt);
  			continue;
  		}
  
  		if (field->value[n] >= min && field->value[n] <= max
  			&& field->value[n] - min < field->maxusage
  			&& field->usage[field->value[n] - min].hid
  			&& search(value, field->value[n], count))
  				hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt);
  
  		if (value[n] >= min && value[n] <= max
  			&& value[n] - min < field->maxusage
  			&& field->usage[value[n] - min].hid
  			&& search(field->value, value[n], count))
  				hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt);
  	}
  
  	memcpy(field->value, value, count * sizeof(__s32));
  exit:
  	kfree(value);
  }
  
  /*
   * Output the field into the report.
   */
  
  static void hid_output_field(const struct hid_device *hid,
  			     struct hid_field *field, __u8 *data)
  {
  	unsigned count = field->report_count;
  	unsigned offset = field->report_offset;
  	unsigned size = field->report_size;
  	unsigned n;
  
  	for (n = 0; n < count; n++) {
  		if (field->logical_minimum < 0)	/* signed values */
  			implement(hid, data, offset + n * size, size,
  				  s32ton(field->value[n], size));
  		else				/* unsigned values */
  			implement(hid, data, offset + n * size, size,
  				  field->value[n]);
  	}
  }
  
  /*
   * Create a report. 'data' has to be allocated using
   * hid_alloc_report_buf() so that it has proper size.
   */
  
  void hid_output_report(struct hid_report *report, __u8 *data)
  {
  	unsigned n;
  
  	if (report->id > 0)
  		*data++ = report->id;
  
  	memset(data, 0, ((report->size - 1) >> 3) + 1);
  	for (n = 0; n < report->maxfield; n++)
  		hid_output_field(report->device, report->field[n], data);
  }
  EXPORT_SYMBOL_GPL(hid_output_report);
  
  /*
   * Allocator for buffer that is going to be passed to hid_output_report()
   */
  u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags)
  {
  	/*
  	 * 7 extra bytes are necessary to achieve proper functionality
  	 * of implement() working on 8 byte chunks
  	 */
  
  	u32 len = hid_report_len(report) + 7;
  
  	return kmalloc(len, flags);
  }
  EXPORT_SYMBOL_GPL(hid_alloc_report_buf);
  
  /*
   * Set a field value. The report this field belongs to has to be
   * created and transferred to the device, to set this value in the
   * device.
   */
  
  int hid_set_field(struct hid_field *field, unsigned offset, __s32 value)
  {
  	unsigned size;
  
  	if (!field)
  		return -1;
  
  	size = field->report_size;
  
  	hid_dump_input(field->report->device, field->usage + offset, value);
  
  	if (offset >= field->report_count) {
  		hid_err(field->report->device, "offset (%d) exceeds report_count (%d)\n",
  				offset, field->report_count);
  		return -1;
  	}
  	if (field->logical_minimum < 0) {
  		if (value != snto32(s32ton(value, size), size)) {
  			hid_err(field->report->device, "value %d is out of range\n", value);
  			return -1;
  		}
  	}
  	field->value[offset] = value;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(hid_set_field);
  
  static struct hid_report *hid_get_report(struct hid_report_enum *report_enum,
  		const u8 *data)
  {
  	struct hid_report *report;
  	unsigned int n = 0;	/* Normally report number is 0 */
  
  	/* Device uses numbered reports, data[0] is report number */
  	if (report_enum->numbered)
  		n = *data;
  
  	report = report_enum->report_id_hash[n];
  	if (report == NULL)
  		dbg_hid("undefined report_id %u received\n", n);
  
  	return report;
  }
  
  /*
   * Implement a generic .request() callback, using .raw_request()
   * DO NOT USE in hid drivers directly, but through hid_hw_request instead.
   */
  int __hid_request(struct hid_device *hid, struct hid_report *report,
  		int reqtype)
  {
  	char *buf;
  	int ret;
  	u32 len;
  
  	buf = hid_alloc_report_buf(report, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	len = hid_report_len(report);
  
  	if (reqtype == HID_REQ_SET_REPORT)
  		hid_output_report(report, buf);
  
  	ret = hid->ll_driver->raw_request(hid, report->id, buf, len,
  					  report->type, reqtype);
  	if (ret < 0) {
  		dbg_hid("unable to complete request: %d\n", ret);
  		goto out;
  	}
  
  	if (reqtype == HID_REQ_GET_REPORT)
  		hid_input_report(hid, report->type, buf, ret, 0);
  
  	ret = 0;
  
  out:
  	kfree(buf);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(__hid_request);
  
  int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
  		int interrupt)
  {
  	struct hid_report_enum *report_enum = hid->report_enum + type;
  	struct hid_report *report;
  	struct hid_driver *hdrv;
  	unsigned int a;
  	u32 rsize, csize = size;
  	u8 *cdata = data;
  	int ret = 0;
  
  	report = hid_get_report(report_enum, data);
  	if (!report)
  		goto out;
  
  	if (report_enum->numbered) {
  		cdata++;
  		csize--;
  	}
  
  	rsize = ((report->size - 1) >> 3) + 1;
  
  	if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE)
  		rsize = HID_MAX_BUFFER_SIZE - 1;
  	else if (rsize > HID_MAX_BUFFER_SIZE)
  		rsize = HID_MAX_BUFFER_SIZE;
  
  	if (csize < rsize) {
  		dbg_hid("report %d is too short, (%d < %d)\n", report->id,
  				csize, rsize);
  		memset(cdata + csize, 0, rsize - csize);
  	}
  
  	if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)
  		hid->hiddev_report_event(hid, report);
  	if (hid->claimed & HID_CLAIMED_HIDRAW) {
  		ret = hidraw_report_event(hid, data, size);
  		if (ret)
  			goto out;
  	}
  
  	if (hid->claimed != HID_CLAIMED_HIDRAW && report->maxfield) {
  		for (a = 0; a < report->maxfield; a++)
  			hid_input_field(hid, report->field[a], cdata, interrupt);
  		hdrv = hid->driver;
  		if (hdrv && hdrv->report)
  			hdrv->report(hid, report);
  	}
  
  	if (hid->claimed & HID_CLAIMED_INPUT)
  		hidinput_report_event(hid, report);
  out:
  	return ret;
  }
  EXPORT_SYMBOL_GPL(hid_report_raw_event);
  
  /**
   * hid_input_report - report data from lower layer (usb, bt...)
   *
   * @hid: hid device
   * @type: HID report type (HID_*_REPORT)
   * @data: report contents
   * @size: size of data parameter
   * @interrupt: distinguish between interrupt and control transfers
   *
   * This is data entry for lower layers.
   */
  int hid_input_report(struct hid_device *hid, int type, u8 *data, u32 size, int interrupt)
  {
  	struct hid_report_enum *report_enum;
  	struct hid_driver *hdrv;
  	struct hid_report *report;
  	int ret = 0;
  
  	if (!hid)
  		return -ENODEV;
  
  	if (down_trylock(&hid->driver_input_lock))
  		return -EBUSY;
  
  	if (!hid->driver) {
  		ret = -ENODEV;
  		goto unlock;
  	}
  	report_enum = hid->report_enum + type;
  	hdrv = hid->driver;
  
  	if (!size) {
  		dbg_hid("empty report\n");
  		ret = -1;
  		goto unlock;
  	}
  
  	/* Avoid unnecessary overhead if debugfs is disabled */
  	if (!list_empty(&hid->debug_list))
  		hid_dump_report(hid, type, data, size);
  
  	report = hid_get_report(report_enum, data);
  
  	if (!report) {
  		ret = -1;
  		goto unlock;
  	}
  
  	if (hdrv && hdrv->raw_event && hid_match_report(hid, report)) {
  		ret = hdrv->raw_event(hid, report, data, size);
  		if (ret < 0)
  			goto unlock;
  	}
  
  	ret = hid_report_raw_event(hid, type, data, size, interrupt);
  
  unlock:
  	up(&hid->driver_input_lock);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(hid_input_report);
  
  bool hid_match_one_id(const struct hid_device *hdev,
  		      const struct hid_device_id *id)
  {
  	return (id->bus == HID_BUS_ANY || id->bus == hdev->bus) &&
  		(id->group == HID_GROUP_ANY || id->group == hdev->group) &&
  		(id->vendor == HID_ANY_ID || id->vendor == hdev->vendor) &&
  		(id->product == HID_ANY_ID || id->product == hdev->product);
  }
  
  const struct hid_device_id *hid_match_id(const struct hid_device *hdev,
  		const struct hid_device_id *id)
  {
  	for (; id->bus; id++)
  		if (hid_match_one_id(hdev, id))
  			return id;
  
  	return NULL;
  }
  
  static const struct hid_device_id hid_hiddev_list[] = {
  	{ HID_USB_DEVICE(USB_VENDOR_ID_MGE, USB_DEVICE_ID_MGE_UPS) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_MGE, USB_DEVICE_ID_MGE_UPS1) },
  	{ }
  };
  
  static bool hid_hiddev(struct hid_device *hdev)
  {
  	return !!hid_match_id(hdev, hid_hiddev_list);
  }
  
  
  static ssize_t
  read_report_descriptor(struct file *filp, struct kobject *kobj,
  		struct bin_attribute *attr,
  		char *buf, loff_t off, size_t count)
  {
  	struct device *dev = kobj_to_dev(kobj);
  	struct hid_device *hdev = to_hid_device(dev);
  
  	if (off >= hdev->rsize)
  		return 0;
  
  	if (off + count > hdev->rsize)
  		count = hdev->rsize - off;
  
  	memcpy(buf, hdev->rdesc + off, count);
  
  	return count;
  }
  
  static ssize_t
  show_country(struct device *dev, struct device_attribute *attr,
  		char *buf)
  {
  	struct hid_device *hdev = to_hid_device(dev);
  
  	return sprintf(buf, "%02x\n", hdev->country & 0xff);
  }
  
  static struct bin_attribute dev_bin_attr_report_desc = {
  	.attr = { .name = "report_descriptor", .mode = 0444 },
  	.read = read_report_descriptor,
  	.size = HID_MAX_DESCRIPTOR_SIZE,
  };
  
  static const struct device_attribute dev_attr_country = {
  	.attr = { .name = "country", .mode = 0444 },
  	.show = show_country,
  };
  
  int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
  {
  	static const char *types[] = { "Device", "Pointer", "Mouse", "Device",
  		"Joystick", "Gamepad", "Keyboard", "Keypad",
  		"Multi-Axis Controller"
  	};
  	const char *type, *bus;
  	char buf[64] = "";
  	unsigned int i;
  	int len;
  	int ret;
  
  	if (hdev->quirks & HID_QUIRK_HIDDEV_FORCE)
  		connect_mask |= (HID_CONNECT_HIDDEV_FORCE | HID_CONNECT_HIDDEV);
  	if (hdev->quirks & HID_QUIRK_HIDINPUT_FORCE)
  		connect_mask |= HID_CONNECT_HIDINPUT_FORCE;
  	if (hdev->bus != BUS_USB)
  		connect_mask &= ~HID_CONNECT_HIDDEV;
  	if (hid_hiddev(hdev))
  		connect_mask |= HID_CONNECT_HIDDEV_FORCE;
  
  	if ((connect_mask & HID_CONNECT_HIDINPUT) && !hidinput_connect(hdev,
  				connect_mask & HID_CONNECT_HIDINPUT_FORCE))
  		hdev->claimed |= HID_CLAIMED_INPUT;
  
  	if ((connect_mask & HID_CONNECT_HIDDEV) && hdev->hiddev_connect &&
  			!hdev->hiddev_connect(hdev,
  				connect_mask & HID_CONNECT_HIDDEV_FORCE))
  		hdev->claimed |= HID_CLAIMED_HIDDEV;
  	if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))
  		hdev->claimed |= HID_CLAIMED_HIDRAW;
  
  	if (connect_mask & HID_CONNECT_DRIVER)
  		hdev->claimed |= HID_CLAIMED_DRIVER;
  
  	/* Drivers with the ->raw_event callback set are not required to connect
  	 * to any other listener. */
  	if (!hdev->claimed && !hdev->driver->raw_event) {
  		hid_err(hdev, "device has no listeners, quitting\n");
  		return -ENODEV;
  	}
  
  	if ((hdev->claimed & HID_CLAIMED_INPUT) &&
  			(connect_mask & HID_CONNECT_FF) && hdev->ff_init)
  		hdev->ff_init(hdev);
  
  	len = 0;
  	if (hdev->claimed & HID_CLAIMED_INPUT)
  		len += sprintf(buf + len, "input");
  	if (hdev->claimed & HID_CLAIMED_HIDDEV)
  		len += sprintf(buf + len, "%shiddev%d", len ? "," : "",
  				((struct hiddev *)hdev->hiddev)->minor);
  	if (hdev->claimed & HID_CLAIMED_HIDRAW)
  		len += sprintf(buf + len, "%shidraw%d", len ? "," : "",
  				((struct hidraw *)hdev->hidraw)->minor);
  
  	type = "Device";
  	for (i = 0; i < hdev->maxcollection; i++) {
  		struct hid_collection *col = &hdev->collection[i];
  		if (col->type == HID_COLLECTION_APPLICATION &&
  		   (col->usage & HID_USAGE_PAGE) == HID_UP_GENDESK &&
  		   (col->usage & 0xffff) < ARRAY_SIZE(types)) {
  			type = types[col->usage & 0xffff];
  			break;
  		}
  	}
  
  	switch (hdev->bus) {
  	case BUS_USB:
  		bus = "USB";
  		break;
  	case BUS_BLUETOOTH:
  		bus = "BLUETOOTH";
  		break;
  	case BUS_I2C:
  		bus = "I2C";
  		break;
  	default:
  		bus = "<UNKNOWN>";
  	}
  
  	ret = device_create_file(&hdev->dev, &dev_attr_country);
  	if (ret)
  		hid_warn(hdev,
  			 "can't create sysfs country code attribute err: %d\n", ret);
  
  	hid_info(hdev, "%s: %s HID v%x.%02x %s [%s] on %s\n",
  		 buf, bus, hdev->version >> 8, hdev->version & 0xff,
  		 type, hdev->name, hdev->phys);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(hid_connect);
  
  void hid_disconnect(struct hid_device *hdev)
  {
  	device_remove_file(&hdev->dev, &dev_attr_country);
  	if (hdev->claimed & HID_CLAIMED_INPUT)
  		hidinput_disconnect(hdev);
  	if (hdev->claimed & HID_CLAIMED_HIDDEV)
  		hdev->hiddev_disconnect(hdev);
  	if (hdev->claimed & HID_CLAIMED_HIDRAW)
  		hidraw_disconnect(hdev);
  	hdev->claimed = 0;
  }
  EXPORT_SYMBOL_GPL(hid_disconnect);
  
  /**
   * hid_hw_start - start underlying HW
   * @hdev: hid device
   * @connect_mask: which outputs to connect, see HID_CONNECT_*
   *
   * Call this in probe function *after* hid_parse. This will setup HW
   * buffers and start the device (if not defeirred to device open).
   * hid_hw_stop must be called if this was successful.
   */
  int hid_hw_start(struct hid_device *hdev, unsigned int connect_mask)
  {
  	int error;
  
  	error = hdev->ll_driver->start(hdev);
  	if (error)
  		return error;
  
  	if (connect_mask) {
  		error = hid_connect(hdev, connect_mask);
  		if (error) {
  			hdev->ll_driver->stop(hdev);
  			return error;
  		}
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(hid_hw_start);
  
  /**
   * hid_hw_stop - stop underlying HW
   * @hdev: hid device
   *
   * This is usually called from remove function or from probe when something
   * failed and hid_hw_start was called already.
   */
  void hid_hw_stop(struct hid_device *hdev)
  {
  	hid_disconnect(hdev);
  	hdev->ll_driver->stop(hdev);
  }
  EXPORT_SYMBOL_GPL(hid_hw_stop);
  
  /**
   * hid_hw_open - signal underlying HW to start delivering events
   * @hdev: hid device
   *
   * Tell underlying HW to start delivering events from the device.
   * This function should be called sometime after successful call
   * to hid_hw_start().
   */
  int hid_hw_open(struct hid_device *hdev)
  {
  	int ret;
  
  	ret = mutex_lock_killable(&hdev->ll_open_lock);
  	if (ret)
  		return ret;
  
  	if (!hdev->ll_open_count++) {
  		ret = hdev->ll_driver->open(hdev);
  		if (ret)
  			hdev->ll_open_count--;
  	}
  
  	mutex_unlock(&hdev->ll_open_lock);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(hid_hw_open);
  
  /**
   * hid_hw_close - signal underlaying HW to stop delivering events
   *
   * @hdev: hid device
   *
   * This function indicates that we are not interested in the events
   * from this device anymore. Delivery of events may or may not stop,
   * depending on the number of users still outstanding.
   */
  void hid_hw_close(struct hid_device *hdev)
  {
  	mutex_lock(&hdev->ll_open_lock);
  	if (!--hdev->ll_open_count)
  		hdev->ll_driver->close(hdev);
  	mutex_unlock(&hdev->ll_open_lock);
  }
  EXPORT_SYMBOL_GPL(hid_hw_close);
  
  struct hid_dynid {
  	struct list_head list;
  	struct hid_device_id id;
  };
  
  /**
   * store_new_id - add a new HID device ID to this driver and re-probe devices
   * @driver: target device driver
   * @buf: buffer for scanning device ID data
   * @count: input size
   *
   * Adds a new dynamic hid device ID to this driver,
   * and causes the driver to probe for all devices again.
   */
  static ssize_t new_id_store(struct device_driver *drv, const char *buf,
  		size_t count)
  {
  	struct hid_driver *hdrv = to_hid_driver(drv);
  	struct hid_dynid *dynid;
  	__u32 bus, vendor, product;
  	unsigned long driver_data = 0;
  	int ret;
  
  	ret = sscanf(buf, "%x %x %x %lx",
  			&bus, &vendor, &product, &driver_data);
  	if (ret < 3)
  		return -EINVAL;
  
  	dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
  	if (!dynid)
  		return -ENOMEM;
  
  	dynid->id.bus = bus;
  	dynid->id.group = HID_GROUP_ANY;
  	dynid->id.vendor = vendor;
  	dynid->id.product = product;
  	dynid->id.driver_data = driver_data;
  
  	spin_lock(&hdrv->dyn_lock);
  	list_add_tail(&dynid->list, &hdrv->dyn_list);
  	spin_unlock(&hdrv->dyn_lock);
  
  	ret = driver_attach(&hdrv->driver);
  
  	return ret ? : count;
  }
  static DRIVER_ATTR_WO(new_id);
  
  static struct attribute *hid_drv_attrs[] = {
  	&driver_attr_new_id.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(hid_drv);
  
  static void hid_free_dynids(struct hid_driver *hdrv)
  {
  	struct hid_dynid *dynid, *n;
  
  	spin_lock(&hdrv->dyn_lock);
  	list_for_each_entry_safe(dynid, n, &hdrv->dyn_list, list) {
  		list_del(&dynid->list);
  		kfree(dynid);
  	}
  	spin_unlock(&hdrv->dyn_lock);
  }
  
  const struct hid_device_id *hid_match_device(struct hid_device *hdev,
  					     struct hid_driver *hdrv)
  {
  	struct hid_dynid *dynid;
  
  	spin_lock(&hdrv->dyn_lock);
  	list_for_each_entry(dynid, &hdrv->dyn_list, list) {
  		if (hid_match_one_id(hdev, &dynid->id)) {
  			spin_unlock(&hdrv->dyn_lock);
  			return &dynid->id;
  		}
  	}
  	spin_unlock(&hdrv->dyn_lock);
  
  	return hid_match_id(hdev, hdrv->id_table);
  }
  EXPORT_SYMBOL_GPL(hid_match_device);
  
  static int hid_bus_match(struct device *dev, struct device_driver *drv)
  {
  	struct hid_driver *hdrv = to_hid_driver(drv);
  	struct hid_device *hdev = to_hid_device(dev);
  
  	return hid_match_device(hdev, hdrv) != NULL;
  }
  
  /**
   * hid_compare_device_paths - check if both devices share the same path
   * @hdev_a: hid device
   * @hdev_b: hid device
   * @separator: char to use as separator
   *
   * Check if two devices share the same path up to the last occurrence of
   * the separator char. Both paths must exist (i.e., zero-length paths
   * don't match).
   */
  bool hid_compare_device_paths(struct hid_device *hdev_a,
  			      struct hid_device *hdev_b, char separator)
  {
  	int n1 = strrchr(hdev_a->phys, separator) - hdev_a->phys;
  	int n2 = strrchr(hdev_b->phys, separator) - hdev_b->phys;
  
  	if (n1 != n2 || n1 <= 0 || n2 <= 0)
  		return false;
  
  	return !strncmp(hdev_a->phys, hdev_b->phys, n1);
  }
  EXPORT_SYMBOL_GPL(hid_compare_device_paths);
  
  static int hid_device_probe(struct device *dev)
  {
  	struct hid_driver *hdrv = to_hid_driver(dev->driver);
  	struct hid_device *hdev = to_hid_device(dev);
  	const struct hid_device_id *id;
  	int ret = 0;
  
  	if (down_interruptible(&hdev->driver_input_lock)) {
  		ret = -EINTR;
  		goto end;
  	}
  	hdev->io_started = false;
  
  	clear_bit(ffs(HID_STAT_REPROBED), &hdev->status);
  
  	if (!hdev->driver) {
  		id = hid_match_device(hdev, hdrv);
  		if (id == NULL) {
  			ret = -ENODEV;
  			goto unlock;
  		}
  
  		if (hdrv->match) {
  			if (!hdrv->match(hdev, hid_ignore_special_drivers)) {
  				ret = -ENODEV;
  				goto unlock;
  			}
  		} else {
  			/*
  			 * hid-generic implements .match(), so if
  			 * hid_ignore_special_drivers is set, we can safely
  			 * return.
  			 */
  			if (hid_ignore_special_drivers) {
  				ret = -ENODEV;
  				goto unlock;
  			}
  		}
  
  		/* reset the quirks that has been previously set */
  		hdev->quirks = hid_lookup_quirk(hdev);
  		hdev->driver = hdrv;
  		if (hdrv->probe) {
  			ret = hdrv->probe(hdev, id);
  		} else { /* default probe */
  			ret = hid_open_report(hdev);
  			if (!ret)
  				ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
  		}
  		if (ret) {
  			hid_close_report(hdev);
  			hdev->driver = NULL;
  		}
  	}
  unlock:
  	if (!hdev->io_started)
  		up(&hdev->driver_input_lock);
  end:
  	return ret;
  }
  
  static int hid_device_remove(struct device *dev)
  {
  	struct hid_device *hdev = to_hid_device(dev);
  	struct hid_driver *hdrv;
  	int ret = 0;
  
  	if (down_interruptible(&hdev->driver_input_lock)) {
  		ret = -EINTR;
  		goto end;
  	}
  	hdev->io_started = false;
  
  	hdrv = hdev->driver;
  	if (hdrv) {
  		if (hdrv->remove)
  			hdrv->remove(hdev);
  		else /* default remove */
  			hid_hw_stop(hdev);
  		hid_close_report(hdev);
  		hdev->driver = NULL;
  	}
  
  	if (!hdev->io_started)
  		up(&hdev->driver_input_lock);
  end:
  	return ret;
  }
  
  static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  
  	return scnprintf(buf, PAGE_SIZE, "hid:b%04Xg%04Xv%08Xp%08X\n",
  			 hdev->bus, hdev->group, hdev->vendor, hdev->product);
  }
  static DEVICE_ATTR_RO(modalias);
  
  static struct attribute *hid_dev_attrs[] = {
  	&dev_attr_modalias.attr,
  	NULL,
  };
  static struct bin_attribute *hid_dev_bin_attrs[] = {
  	&dev_bin_attr_report_desc,
  	NULL
  };
  static const struct attribute_group hid_dev_group = {
  	.attrs = hid_dev_attrs,
  	.bin_attrs = hid_dev_bin_attrs,
  };
  __ATTRIBUTE_GROUPS(hid_dev);
  
  static int hid_uevent(struct device *dev, struct kobj_uevent_env *env)
  {
  	struct hid_device *hdev = to_hid_device(dev);
  
  	if (add_uevent_var(env, "HID_ID=%04X:%08X:%08X",
  			hdev->bus, hdev->vendor, hdev->product))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "HID_NAME=%s", hdev->name))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "HID_PHYS=%s", hdev->phys))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "HID_UNIQ=%s", hdev->uniq))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "MODALIAS=hid:b%04Xg%04Xv%08Xp%08X",
  			   hdev->bus, hdev->group, hdev->vendor, hdev->product))
  		return -ENOMEM;
  
  	return 0;
  }
  
  struct bus_type hid_bus_type = {
  	.name		= "hid",
  	.dev_groups	= hid_dev_groups,
  	.drv_groups	= hid_drv_groups,
  	.match		= hid_bus_match,
  	.probe		= hid_device_probe,
  	.remove		= hid_device_remove,
  	.uevent		= hid_uevent,
  };
  EXPORT_SYMBOL(hid_bus_type);
  
  int hid_add_device(struct hid_device *hdev)
  {
  	static atomic_t id = ATOMIC_INIT(0);
  	int ret;
  
  	if (WARN_ON(hdev->status & HID_STAT_ADDED))
  		return -EBUSY;
  
  	hdev->quirks = hid_lookup_quirk(hdev);
  
  	/* we need to kill them here, otherwise they will stay allocated to
  	 * wait for coming driver */
  	if (hid_ignore(hdev))
  		return -ENODEV;
  
  	/*
  	 * Check for the mandatory transport channel.
  	 */
  	 if (!hdev->ll_driver->raw_request) {
  		hid_err(hdev, "transport driver missing .raw_request()\n");
  		return -EINVAL;
  	 }
  
  	/*
  	 * Read the device report descriptor once and use as template
  	 * for the driver-specific modifications.
  	 */
  	ret = hdev->ll_driver->parse(hdev);
  	if (ret)
  		return ret;
  	if (!hdev->dev_rdesc)
  		return -ENODEV;
  
  	/*
  	 * Scan generic devices for group information
  	 */
  	if (hid_ignore_special_drivers) {
  		hdev->group = HID_GROUP_GENERIC;
  	} else if (!hdev->group &&
  		   !(hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)) {
  		ret = hid_scan_report(hdev);
  		if (ret)
  			hid_warn(hdev, "bad device descriptor (%d)\n", ret);
  	}
  
  	/* XXX hack, any other cleaner solution after the driver core
  	 * is converted to allow more than 20 bytes as the device name? */
  	dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,
  		     hdev->vendor, hdev->product, atomic_inc_return(&id));
  
  	hid_debug_register(hdev, dev_name(&hdev->dev));
  	ret = device_add(&hdev->dev);
  	if (!ret)
  		hdev->status |= HID_STAT_ADDED;
  	else
  		hid_debug_unregister(hdev);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(hid_add_device);
  
  /**
   * hid_allocate_device - allocate new hid device descriptor
   *
   * Allocate and initialize hid device, so that hid_destroy_device might be
   * used to free it.
   *
   * New hid_device pointer is returned on success, otherwise ERR_PTR encoded
   * error value.
   */
  struct hid_device *hid_allocate_device(void)
  {
  	struct hid_device *hdev;
  	int ret = -ENOMEM;
  
  	hdev = kzalloc(sizeof(*hdev), GFP_KERNEL);
  	if (hdev == NULL)
  		return ERR_PTR(ret);
  
  	device_initialize(&hdev->dev);
  	hdev->dev.release = hid_device_release;
  	hdev->dev.bus = &hid_bus_type;
  	device_enable_async_suspend(&hdev->dev);
  
  	hid_close_report(hdev);
  
  	init_waitqueue_head(&hdev->debug_wait);
  	INIT_LIST_HEAD(&hdev->debug_list);
  	spin_lock_init(&hdev->debug_list_lock);
  	sema_init(&hdev->driver_input_lock, 1);
  	mutex_init(&hdev->ll_open_lock);
  
  	return hdev;
  }
  EXPORT_SYMBOL_GPL(hid_allocate_device);
  
  static void hid_remove_device(struct hid_device *hdev)
  {
  	if (hdev->status & HID_STAT_ADDED) {
  		device_del(&hdev->dev);
  		hid_debug_unregister(hdev);
  		hdev->status &= ~HID_STAT_ADDED;
  	}
  	kfree(hdev->dev_rdesc);
  	hdev->dev_rdesc = NULL;
  	hdev->dev_rsize = 0;
  }
  
  /**
   * hid_destroy_device - free previously allocated device
   *
   * @hdev: hid device
   *
   * If you allocate hid_device through hid_allocate_device, you should ever
   * free by this function.
   */
  void hid_destroy_device(struct hid_device *hdev)
  {
  	hid_remove_device(hdev);
  	put_device(&hdev->dev);
  }
  EXPORT_SYMBOL_GPL(hid_destroy_device);
  
  
  static int __hid_bus_reprobe_drivers(struct device *dev, void *data)
  {
  	struct hid_driver *hdrv = data;
  	struct hid_device *hdev = to_hid_device(dev);
  
  	if (hdev->driver == hdrv &&
  	    !hdrv->match(hdev, hid_ignore_special_drivers) &&
  	    !test_and_set_bit(ffs(HID_STAT_REPROBED), &hdev->status))
  		return device_reprobe(dev);
  
  	return 0;
  }
  
  static int __hid_bus_driver_added(struct device_driver *drv, void *data)
  {
  	struct hid_driver *hdrv = to_hid_driver(drv);
  
  	if (hdrv->match) {
  		bus_for_each_dev(&hid_bus_type, NULL, hdrv,
  				 __hid_bus_reprobe_drivers);
  	}
  
  	return 0;
  }
  
  static int __bus_removed_driver(struct device_driver *drv, void *data)
  {
  	return bus_rescan_devices(&hid_bus_type);
  }
  
  int __hid_register_driver(struct hid_driver *hdrv, struct module *owner,
  		const char *mod_name)
  {
  	int ret;
  
  	hdrv->driver.name = hdrv->name;
  	hdrv->driver.bus = &hid_bus_type;
  	hdrv->driver.owner = owner;
  	hdrv->driver.mod_name = mod_name;
  
  	INIT_LIST_HEAD(&hdrv->dyn_list);
  	spin_lock_init(&hdrv->dyn_lock);
  
  	ret = driver_register(&hdrv->driver);
  
  	if (ret == 0)
  		bus_for_each_drv(&hid_bus_type, NULL, NULL,
  				 __hid_bus_driver_added);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(__hid_register_driver);
  
  void hid_unregister_driver(struct hid_driver *hdrv)
  {
  	driver_unregister(&hdrv->driver);
  	hid_free_dynids(hdrv);
  
  	bus_for_each_drv(&hid_bus_type, NULL, hdrv, __bus_removed_driver);
  }
  EXPORT_SYMBOL_GPL(hid_unregister_driver);
  
  int hid_check_keys_pressed(struct hid_device *hid)
  {
  	struct hid_input *hidinput;
  	int i;
  
  	if (!(hid->claimed & HID_CLAIMED_INPUT))
  		return 0;
  
  	list_for_each_entry(hidinput, &hid->inputs, list) {
  		for (i = 0; i < BITS_TO_LONGS(KEY_MAX); i++)
  			if (hidinput->input->key[i])
  				return 1;
  	}
  
  	return 0;
  }
  
  EXPORT_SYMBOL_GPL(hid_check_keys_pressed);
  
  static int __init hid_init(void)
  {
  	int ret;
  
  	if (hid_debug)
  		pr_warn("hid_debug is now used solely for parser and driver debugging.\n"
  			"debugfs is now used for inspecting the device (report descriptor, reports)\n");
  
  	ret = bus_register(&hid_bus_type);
  	if (ret) {
  		pr_err("can't register hid bus\n");
  		goto err;
  	}
  
  	ret = hidraw_init();
  	if (ret)
  		goto err_bus;
  
  	hid_debug_init();
  
  	return 0;
  err_bus:
  	bus_unregister(&hid_bus_type);
  err:
  	return ret;
  }
  
  static void __exit hid_exit(void)
  {
  	hid_debug_exit();
  	hidraw_exit();
  	bus_unregister(&hid_bus_type);
  	hid_quirks_exit(HID_BUS_ANY);
  }
  
  module_init(hid_init);
  module_exit(hid_exit);
  
  MODULE_AUTHOR("Andreas Gal");
  MODULE_AUTHOR("Vojtech Pavlik");
  MODULE_AUTHOR("Jiri Kosina");
  MODULE_LICENSE("GPL");
  